Disney/Pixar’s popular animated movie Monsters, Inc opened on November 2, 2001, becoming a worldwide success. It followed the adventures of two monsters working for a company that generated the city’s power by scaring children. It introduced audiences to James P Sullivan, aka Sulley (voiced by John Goodman, Argo, Flight), the company’s top Scarer, and his assistant and best friend, the one-eyed Mike Wazowski (voiced by Billy Crystal,When Harry Met Sally…, Parental Guidance)

Twelve years later, the prequel Monsters University opens this week, on June 21st, which chronicles how Sulley and Mike first meet. But college life turns out to be a challenge for both of them, where their relationship is far from friendly.

Billy and John got together to speak about returning to the franchise and their love for their characters.

What is it about Sulley and Mike that resonates with you?

No, I think the reason they work so well together is that they complete each other in a way. I think Sulley really needs Mike Wazowski. They learn how to adapt, how to let go of their pre-conceived notions of themselves and of the world. They’re good for each other.

Billy: For me, Mike is fearless. He’s really the favorite character I’ve ever played in anything I’ve done, and playing off of John is phenomenal because we worked together in the studio. I think that’s why their relationship on screen is real.

It was so fun to revisit them at this time in their lives. It was such a brilliant idea to put them in that time period when they’re about to become who they’re gonna become. That’s what was so interesting to me.

Was it challenging to you to do younger versions of the characters?

Billy: The first day that we reported to work together, they showed us renderings of the guys, and we just started laughing. Sulley’s a little trimmer, Mike’s got a retainer, and there’s a little more youth in his eye! They just carry themselves differently. It’s subtle, but it’s there.

John: With the voice, I thought I was gonna come in and talk like the kid from Our Miss Brooks, [but] it just happened organically. You pick up on other energies and the characters’ focuses, and it just happens. It’s a subtle difference.

What did you think of Helen Mirren voicing the head of the university, Dean Hardscrabble?

Billy: Well, she’s aristocracy. She’s Dame Helen. I wish we had been around when she was working. She’s just fantastic. She commands, even in a strangely animated dragon, whatever she was, there’s a regalness to her, and her voice is perfect. It was great casting.

What used to scare you as a child?

John: Frankenstein. That scared the heck out of me. But I loved those movies.

Billy: I still don’t like the darkness, though I’ve learned to smile in it a little bit now and then. The unknown has always been a little scary when you think about those things, especially as you get older. Boy, that got heavy!

Billy and John were asked how Pixar has changed since they made the first movie. Click here to see their answer.